Steam has broken the six million user mark for simultaneous users, due partly to their ever growing user base, but also much thanks to the seasonal Steam sale.
Over six million users were recently logged into Steam at the same time, breaking the next million user barrier after hitting five million earlier this year. This is partly due to the seasonal Steam sale currently ongoing, which offers deals on newly released titles as well as anthologies of old games. However, as the most played game on Steam right now is the free-to-play DOTA 2, these stats may not be entirely temporary. Unfortunately, the consoles aren't releasing simultaneous user stats as openly as Steam is, so it's difficult to say how the platforms compare, but no doubt PC gaming is far from dead.
Over 6 million user at once. Impressive!
Steam was originally released by Valve in 2003 as a platform for updating Counter-Strike, but soon grew into a software distribution platform and social hub for PC gamers, and in later years, has also seen a release for Mac, PS3 and Mobile platforms, and a version is in the works for Linux as well. In 2011, Forbes announced that Steam accounted for 50-70% of digital game sales for the PC and The Witcher II has similarly stated that Steam accounts for 80% of their digital sales.